Alternating current measurement is an important detection object in electric energy measurement; conventional alternating current measurement methods comprise: high resistance and voltage dividing method with a multi-meter; electro-magnetic converting method with a transformer; electro-magnet-elector measurement method with a turbine watt-hour meter. Mature products according to above methods are applied in meters, industry and household applicability, and widely applied.
However, if long and continuous online measurement is desired, especially in mass and widespread distribution detection, the conventional methods result in an inevitable problem, on one hand, that is energy consumption. An additional auxiliary energy consumption component is needed for sampling so that the alternating current could be detected; no matter in the external voltage dividing resistance of the high resistance and voltage dividing method or in the electro-magnetic converter; it inevitably causes continuous energy consumption; in the other hand, the energy consumption component consumes relative hardware, thus not only adding the cost unavoidably but also consuming resource; for example silicon steel plate, insulation material and copper line material are needed when applying the electro-magnetic converter.